1. Field of the Invention
The present invention relates to a floating type disc brake used for a vehicle such as a motorcycle.
2. Description of Background Art
In such a floating type disc brake, the thermal expansion caused in a braking rotor by heat generation in the braking rotor during braking operation is adapted to be absorbed by a predetermined gap formed by arranging and connecting the braking rotor and a hub via the gap and thus problems such as deformation of the braking rotor caused by the thermal expansion can be solved. However there is a further problem that the braking rotor itself is liable to be heated to a high temperature since the heat caused in the braking rotor during braking operation is difficult to be conducted to the hub.
There has been provided, e.g. in a first prior art, a floating type disc brake in which the braking rotor comprises an annular rotor portion and a plurality of projections extending radially inward from the inner circumferential portion of the rotor portion, and the rotor portion and the hub arranged inside the annular braking rotor are connected by connecting means in a floating manner each other with the projections being abutted to the outer circumferential portion of the hub and heat transferring members being arranged between the projections of the braking rotor and the hub (see e.g. Claims of Japanese Laid-open Patent Publication No. 303342/2002).
In such a floating type disc brake, it has been required to have a necessary strength and to reduce its weight as light as possible in order to improve the fuel consumption of a vehicle equipped with the disc brake. There has been also provided, e.g. in a second prior art, a floating type disc brake in which either the braking rotor and the hub are formed with a plurality of through apertures over whole surfaces of them and the outer circumferential portion of the hub is additionally formed with through apertures so that beam-like portions each having a circular arc configuration are remained therealong. (see e.g. FIG. 1 of Japanese Laid-open Patent Publication No. 227891/2002).